So, is your question rather, "Backbores on PRANA mouthpieces appear to be very open - has anyone done this before?" And I think the answer to that would be consistent with question 1) - "Yes."

Not to issue such a flippant answer to what you're trying to find out, but please let us know what you're thinking about which has led to this question. I really respect Monette's design innovations, and choose his equipment for my music making, however if you look at two different sized PRANA mouthpieces, you'll notice differences in terminal diameter, which impacts certain viewable/measurable variants in the overall taper.
Additionally, the throat size has an impact, and there are backbore shapes, classed as 77, 79, 81, 82, 84, 88, 92, 94, etcetcetc - so it should be clear by now, "PRANA backbore" isn't a single, monolithic thing.

That said, I've been playing various PRANA mouthpieces essentially since they were first rolled-out, and haven't looked back.

Happy practicing, and I look forward to learning more about what you're trying to ask about here.

I play on a Kanstul copy of a Prana, which is not SLAP and not Resonance. It's very open, clear, rich, and I get "more trumpet out of my trumpet" when I use it, compared to any other mp I've tried. I also have a Monette Silver Series 4, whose resistance feels like most non-Monette mouthpieces. So I'm curious if the Prana backbore is magic secret sauce that's never been discovered before.

My question and my ability are not very strong, and probably don't warrant much effort in response.

I was really just looking for an answer like "Yeah, its a lot like the mouthpieces Fatty Cazutto made in the basement of his father's barber shop in the late 1950's. In fact it's pretty much a direct ripoff".

or,

"No, nothing like it has ever been done before."

That's about how deep I can go on the subject._________________Courtois Evolution IV
Bach 7 mp, drilled to 21

The issue really is that each Monette prana mouthpiece has a different backbore from every other one because the length from the throat to the shank end will be slightly different. Also, the different keyed versions are all different overall lengths.

This is my gut feeling having played Monette mouthpieces, and trumpet, for a number of years previously. Daniel may disagree, but I found that the Prana mouthpieces worked well on the Prana instruments but the equivalent STC1 Prana mouthpieces did not work as well on non monette equipment. I think the non Monette instruments were making me use too much muscle and the prana mouthpieces did not like that. So I learned to stick with STC1 non prana on my non monette instruments.

Other people have said the same thing, but others disagree. I guess it will depend on your approach to playing and exactly what equipment you are playing on._________________Bb - Scherzer 8218W, Bach 43, Selmer 19A Balanced
Pic - Weril
Flugel - Courtois 154
Cornet - Besson Prestige, Conn 81A New Wonder
Mouthpieces - MV 3C variants by Breslmair & Horntrader

Putting aside the holistic aspect I would be interested on the history of mouthpieces which are all of

1) a bit shorter length overall,
2) have a bigger throat, and
3) have a more strongly conical backbore (they widen more over the length - a fat cone as opposed to a thin cone).

Note you need 1) to do 3) well, and 2) is fighting with 3) in the design space.

From my limited knowledge,
1) shorter (and longer) mouthpieces are historically common.
2) Big throats are also out there in older pieces, I have a few.
3) I have personally never seen a mouthpiece as conical over the length of the backbore, even accounting for the wider throat.

freddie webster would take a mouthpiece, drill out the throat a bunch, then shorten the shank, then flare out the end

thats pretty much a prana_________________Mouthpiece Maker
vintage Trumpet design enthusiast
www.meeuwsenmouthpieces.comwww.lipshurt.com
All of my posts are done with my phone on the fly, and it will sometimes auto-correct in some pretty unusual ways. Think of it like a crossword:)

Dizzy calls his sound "the best I ever heard" and recounts that Freddie once gave him some mechanical help. "One time I had a Blessing mouthpiece. He took it and cut off the end. Not only that, but he made a bigger hole--the back bore. He pulled my coat to that--the shorter mouthpiece. You get to the note quicker."

I guess the question is refinement (ie: making a bunch of variations and choosing the best) and repeatability - in that sense, perhaps, Monette could be seen to be doing something already out there but with a quality with which it hadn't been commonly done.

freddie webster would take a mouthpiece, drill out the throat a bunch, then shorten the shank, then flare out the end

thats pretty much a prana

I think it's a bit more involved than that. I have a Curry 1BC short shank (factory). Stock 24 throat, #2 backbore. It appears to get around the significant step created by chopping .4" off the end, the backbore has been flared. This creates a sort of dual backbore and it doesn't look anything like any prana I've looked at, which all had consistent shapes without sudden changes._________________-Tom Hall-
Bach 37 B flat
Benge 8Z Bb Cornet
Bach 239 C w/Akright Leadpipe
Stomvi Piccolo

Every shortened mouthpiece I have seen also has a flared end. Also, its relatively easy to by hand flare the end whereas making an even conical shape for the entire run of the backbore is extremely difficult without a custom reamer.

Dizzy calls his sound "the best I ever heard" and recounts that Freddie once gave him some mechanical help. "One time I had a Blessing mouthpiece. He took it and cut off the end. Not only that, but he made a bigger hole--the back bore. He pulled my coat to that--the shorter mouthpiece. You get to the note quicker."

Its not clear if he only widened the throat, or the rest of the backbore as well.

Thanks for finding that old post by Lips, Scott. It answers my question very well._________________Courtois Evolution IV
Bach 7 mp, drilled to 21